JPS5975454A - Tape loop sensing arm for magnetic tape recorder/reproducer and tape guide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Background of the Invention The present invention d: - Concerns a tape guide for use in a magnetic tape recording/reproducing machine 1, in particular, a tape constituting a part of a machine for recording and reproducing video signals. The present invention relates to a tape guide forming part of a tape loop sensing arm in a transport device.

In most magnetic tape recording and playback machines, magnetic tape is transported from a tape feed reel, through a recording head, to a take-up reel in a path defined by a plurality of guides.The tape typically has a diameter It is driven by a capstan that engages the tape at appropriate locations on the road. The feed and take-up reels are driven via motors controlled by servomechanisms to maintain the proper tension on the tape. In video machines, the tape path extends proximate 17 to the rotating scanner. The scanner, in the case of a helical scan video machine, comprises a drum that guides the tape along a helical path so that it is scanned by a scanning head driven at high speed in an initial number of diagonal tracts. In many types of magnetic tape recording and playback, it is desirable to precisely control the tape speed, but especially in video machines, as is well known, it is desirable to maintain a substantially constant tape tension. It is highly desirable to control the motors driving the tape advance and take-up reels to avoid loading the capstan from the tape reel.

In order to monitor the tape tension in the tape section in close proximity to either the feed or take-up reel, an arm is pivotally mounted at one end and carries a roller-type guide at the other end for guiding the tape. It is well known that this is provided. The tape path extending through the roller type guide carried by this arm cooperates with the upstream and downstream guides of the arm in the direction of tape travel to form a small A-p. Pivoting of the arm allows the roller-type guide to swing, for example, along an arcuate path, and the arm is typically biased in a direction that maximizes the length of the tape loop. It is common to have one such pivot arm and roller-type guide near the feed reel and one near the take-up reel, e.g. near the feed reel6. Considering the case of a pivot arm, as the tension in the loop of tape formed by a roller-type guide carried on the pivot arm increases, the pressure of the tape acting on the guide increases, causing the guide to It is moved along an arcuate path extending in a plane perpendicular to its axis and the pivot line of the pivot arm. The resulting pivoting movement of the pivoting arm is controlled by suitable means (
Detection 17 (not directly relevant to the present invention) makes it possible to obtain a signal representative of the loop length and thus of the tape tension.

As is well known, the signals can also be readily used as part of a servo lube to control the feed reel motor to accommodate variations in tape tension. write[
7, the feed reel motor can be driven to speed up or slow down as needed, thereby relaxing or increasing the tension applied to the tape by the feed reel, thereby causing the pivot arm to The tape tension monitored by the tape tension is maintained substantially constant. As will be apparent to those skilled in the art, the tension sensing arm (pivoting arm) associated with the take-up reel is similar to the sense arm of the feed reel and the tension sensing arm associated with the take-up reel is The circuitry includes a mode switching device for controlling the motor differently depending on the particular mode of operation of the tape transport required, such as fast forward or rewind.

The pressure exerted by the tape on the guide carried by the tension-sensing arm is so great that the bearings for the guide are susceptible to wear, and roller-type guides are attached to the post by monoclinic bearings. In this case, there will be play in the bearings, which will lead to inaccurate tape guidance.Furthermore, tape wear can be considerable, which will generally have a substantial effect on the accuracy of the sensing arm. It is desirable that the height of the tape be able to absorb small fluctuations in tension so as to reduce wear without causing wear.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rotating tape guide which reduces wear and resultant rattle of the bearing assembly of the guide basin.

Another object of the present invention is to provide a tape guide with an improved structure. The tape loop is to provide a sensing arm.

According to the present invention, a spindle is attached to the rotary tape guide carried by the detection arm so that the rotary tape guide can be rotated about an axis that is upright with respect to the nuclear arm.
71 rotation axis vs. 1. The face angle can be pivoted about a central axis. In other words, it is possible to tilt the rotation axis sub-axis of the rotation guide. 4. Drive of the handle, and thus the tilting of the guide, when the sensing arm is in the intermediate position, causes the plane of the tape ( It is preferable to revise said tilting axis of the spindle so that it takes place in a plane parallel to said plane. The rotating guide is thus allowed to float practically in said plane, Moreover, even if the guide is pivoted or tilted within certain limits, the top and bottom of the guide remain at the same distance from the pivot axis of the pivot arm, and the loops between the top and bottom edges of the tape Since the length is also maintained the same length, there is little disturbance to the guide of the tape.Moreover, the tilting of the guide in the above plane causes little change in the angular position of the pivot sensing arm for a given loop length. Therefore, it is possible to avoid disturbing the sensing accuracy of the tension of the tape loop.

BRIEF DESCRIPTION OF THE DRAWINGS The diagonal and other objects and advantages of the present invention will become apparent from the following description and description of the embodiments taken in conjunction with the accompanying drawings.

FIG. 1 shows a simplified diagram of the main components of a video tape recorder. The video tape recorder 1 shown in FIG. 1 is for recording signals on a magnetic tape fed out from a feed reel 3 driven by a motor (not shown) or for reproducing signals from the tape. .

The path e of the tape 2 from the feed reel 5 passes through the rotatable guide boss (A) and reaches the rotary guide 5 carried by one end of the sensing arm 6 which is coaxial with the post 4 in several cases.

The sensing arm 6 is pivotable in the plane of travel of the tape 2.

From the rotary guide 5 the tape path passes through a guide post 7 and radially through the video erasing head 8 to a pair of entry guides 9 which control the introduction of the tape into a helical path around the scanning drum 10. The axis 11 of the drum 10 is slightly inclined with respect to the overall plane of the tape path from the feed reel 3 to the drum. A motor is provided to drive a scanning head for scanning around the outer circumference of the drum. At the end of the helical path around the drum the tape is defined and controlled by a pair of exit guides 12. These two pairs of inlet guides 9 and outlet guides 12 define an "omega"-shaped circumferential path around the scanning drum. 0 Next, the tape passes through the guide 13,
Cap stun 14 and pinch roller 1 pressed against it
5, the erase head 16, the audio head 17 and the control track head 18 pass through the fixed
It passes through the id 19 and along the guides 20 and 22 to the take-up reel 25. As in the case of the guide 5, the guide 20 has a pivotable arm 2 added coaxially with the guide 22.
This is a guide attached to one end of the guide 1 and functions similarly to the guide 5. That is, the position of the arm 21 is the same as that of the guides 19 and 22.
represents a measure of the tension in a loop of tape extending between
Servo motor (not shown) that drives the take-up reel 23
A reservoir control signal is provided to enable the tension in the tape loop to be maintained substantially constant.

To simplify the illustration, the controls and motors of the scanning head, capstan o, and take-up reel reservoir are highlighted.

As is well known, the reservoir for controlling the tape tension involves adjusting the length of the tape loop engaged by the tape guides of the sensing arms 6, 21 from the tray 1111 to the motors of the feed and take-up reel reservoirs accordingly. It is better to control the operation. The manner in which the length of the tape loop is monitored 2 and the motor is controlled does not form part of the present invention, but
For example, if the tape tension in the tape loop engaged by the roller-type guide 5 at one end of the sensing arm 6 increases, the arm 6
is clearly pivoted. The pivoting movement of the arm 6 is effected by the spring force of a return spring (not shown). The pivot +d of the arm 6 can be detected by known suitable means and used as an error signal in the servo-mechanical control 1 of the feed reel 5 to increase or decrease the speed of the reel and to adjust the tape tension. To restore the desired intermediate value, the tape is rotated around the guide 5 (not yet 20) when the tape is under the required tension, with its associated arm 6 (or 21) in its intermediate position. It is preferable to turn it approximately 90 degrees.

FIG. 2 shows the kite 4, guide 5 and arm 6 assembly, including the mechanical parts of the detector for indicating the angular position of the arm.

The deck 24 of the video tape recorder has a dish-shaped recess 25.
A central hole 2 is formed at the bottom of the concave recess for receiving a compatible axis 27 perpendicular to the plane of the arm 6.
6 is drilled.

I11] 27 extends downwardly from the sensing arm 6 through the hole 26 of the dish-shaped recess 25, and in the lower part of the shaft 27,
A sector-shaped insulating plate 28 is mounted below the arm 6 and parallel to the arm. The plate 28 is carried on a collar 29 which is fixed to the shaft 27. A bushing 30 is attached to the lower side of the collar 29 so as to surround the shaft 28, a collar 32 is disposed below the bushing 30, and the collar 32 is seated on a seat 32 disposed on a lower deck 33. Plate 28 forms part of the t# detector. The plate 28 is made of a rigid plastic material and carries a strip 54 of damping material, for example a non-magnetic metal such as copper or ferrite. The plate 28 cooperates with a magnetic sensing head 35 which is constituted by a core 37 having a gap 38 into which the plate protrudes, and a coil 36 wound around the core. The core 37 is carried by a bracket 39 fixed to the deck 24 by screws 40.

Although not important in the context of the present invention, the coil 36 is adapted to form part of an oscillator circuit whose Q changes as the plate 28 moves within the gap 38, and the strip 64 a dish-shaped recess 25 shaped to establish a proportional relationship between the output of the oscillator, part of which is constituted by the coil 56, and the variation in tape tension causing the pivoting of the arm 6; The shaft 27 housing the bearing A1 for the shaft 27 has a collar 42 supported by a bearing 41.
and supports the arm 6.

That is, a bush 43 provided at the inner end of the arm 6 is keyed to the shaft 27.

A bearing 44 is supported by a bush 45 . The bearing 44 cooperates with the upper bearing 45 to support the cylindrical guide member 46.
is attached to the shaft 27 so as to be rotatable about its longitudinal axis. The guide side 46 has internal flanges 47.48 which engage bearings 44.45.

The top end d1 of the shaft 27, the bearing 4 held in the cap 50
It is supported by 9. Below the bearing 49 (111) there is a downwardly directed flange 52 extending downwardly and projecting between the two bidirectional annular flanges 55 and 54 of the annular body 55.
An annular plate 51 is provided. Annular body 5
5 is fixed within the guide member 46 and presses the bearing 45. The flanges 52, 53, 5A constitute a dust trap. A compression coil spring 56 surrounding the shaft 27 is disposed between the plate 51 and the bearing 45. To stiffen the shaft 27, the cap 50 can be secured to a suitable frame member (not shown) that extends to the deck 24 so as not to interfere with tape feed.

The outer end of arm B is a thick part 57 that is thicker than other parts of the arm.
have. Portion 57 is provided with seven holes 58 for supporting upright hollow posts 59. The post 59 slightly protrudes from the lower surface of the portion 57, and the upper surface of the deck 24 is provided with a connection between the lower end of the post 59 and the deck 24 over the range of the arcuate path along which the outer end of the pivot sensing arm moves. An arcuate recess 60 is formed so as to form a sufficient clearance therebetween.

The post 59 has a cylindrical peripheral wall 61 , the upper end of which is shaped to form an inverted yoke 62 . Holes 63 .diametrically opposed to each other are formed in the yoke 62 .
Through 65 an axle 64 is inserted parallel to arm 6 and thus in the radial direction of the pivot axis of arm 6 defined by axis 27 .

The axle 64 constitutes a pivot shaft for the spindle 65. The spindle 65 has an upper portion 66, an intermediate portion 67 having a somewhat larger diameter, and a lower portion 68. The intermediate portion 671r of the spindle constitutes the nozzle of the axle 64 and allows the spindle 65 to pivot about the 1h line of the axle 64. The foot 69 extends downwardly into the interior of the post 59 and has a foot 69 having a slight clearance between it and the wall 61 of the post 59 . This clearance cannot be clearly shown in the figure. However, since the wall 61 and foot 59 are cylindrical, the critical dimension of this clearance is the dimension perpendicular to the plane of FIG. It is represented by the gap 70 between the foot 59 and the wall 61.

Spindle 65 carries a collar 71 at its upper end. Two bearings 72, 73 support the spindle 65 on the underside of the collar 71. The bearings 72, 751d constitute a rotary attachment means for the cylindrical guide portion 1FA7A for guiding the tape through. The guide part side 74 has a cylindrical outer surface 75 (7, with rims 76 and 77 at both upper and lower ends).
have. A bearing 72 is provided on the inner surface of the guide portion side 74.
Internal lips 78 and 79 are formed between and 73. A top cover 81 has a downwardly extending annular lip 82 that fits inside the inner peripheral surface of its cylindrical wall. It is equipped with

With the above configuration, the guide member 74 can rotate about an axis in a plane tangential to the arcuate pivot trajectory of the outer end of the sensing arm 6, and the axle 64 can rotate in this same plane. can be pivoted or tilted about an axis defined by. Pivotal movement of guide member 74 is limited to an angular range of 2 to 3 degrees by engagement of foot 69 with the inner surface of wall 61 of post 59.

In the position of the arm 6 when the tape tension is at the desired or design value, the arm 6 and the axle 64 are positioned relative to the portion of the tape path that extends from the guide 5 in the direction opposite to the side on which the reel 6 is located. They form a right angle. Thus, the pivot sensing arm 6
in this position, the guide 5 can 'float' in the plane of the tape with little change in the effective length of the sensing arm 6 □ The pivot axis 6 of the guide 5 is above the tape. Since it is centered between the edge and the lower edge, the arm 6 is aligned with the axis (2
7), the effective length of the arm 6 hardly changes even if the angle between the arm 6 and the tape path becomes greater than 90°. The effective length of the arm 6 is the distance between the axis of the shaft 27 and the point where the tape leaves the outer surface of the guide 5.

The accuracy of the sensing arm B is considerably aided by providing the rotary guide 4 in a fixed position coaxially with the pivot axis of the arm 6.

Although embodiments of the invention have been described in relation to a tape tension sensing arm carrying a rotating guide, various variations are possible within the scope of the invention. For example, the spindle 65 of the guide 5 may be pivotally mounted in a gimballed manner. That is, the ball in the socket provided in the middle between the upper and lower ends of the guide part phase 74 is fitted, and the spindle 6 is fitted into this ball.
5 can be mounted and arranged so that the spindle can pivot through a certain angular range about the ball.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a tape conveying device to which a sensing arm equipped with a guide of the present invention can be applied. FIG. 2 is a sectional view of a tape tension sensing arm equipped with a guide of the present invention. In the figure, 4 rotation guides, 5 rotation guide, 6 sensing arm,
27 is a pivot shaft, 59 is a post, 61 is a peripheral wall, 64 is a wheel 4
11 (pivot axis), 65 is the spindle, 69 is the foot, 72
．． 73 is a bearing, and 74 is a guide portion.

Claims (1)

Claims: 1) in a tape loop sensing arm that guides the tape and pivots in response to variations in the tape loop, pivot axis means defining a first pivot axis; an arm member mounted for rotation about a first pivot axis; a cylindrical tape-engaging guide portion; and an arm member mounted for rotation about a first pivot axis; support means attached to said arm member for rotation and tape guidance, said support means being oriented opposite 17 to said first pivot axis without substantially altering the effective sensing length of said arm member; A tape loop sensing arm adapted to permit pivoting of said guide member about a second orthogonal pivot axis. 2) The support means includes a spindle that defines the rotational axis, a bearing that attaches the guide portion so as to be rotatable about the spindle, and a bearing that attaches the spindle so that it can freely pivot about the second pivot axis. 2. A tape loop sensing arm according to claim 1, further comprising attachment means for a tape loop. 3) The tape according to claim 2, wherein the attachment means comprises a post supporting an axle to which the spindle throat is attached. - Tape loop sensing arm 04) The tape loop sensing arm according to claim 2 is provided with a limiting means for restricting the pivoting of the spindle. 5) The post U' hollow interior. 11. the extension of the spindle fits into the hollow interior of the post; , a tape loop sensing arm according to claim 6, adapted to define a constant clearance between the extension and the post. 6) a tape loop sensing arm configured to rotate coaxially with the first pivot axis; 6. A table sensing arm according to claim 1, further comprising a rotating tape guide mounted on the table. 7) a tape loop sensing arm having a pivotable support and a support adapted to engage the tape and rotate about an axis of rotation, and to respond to variations in the tension of the engaged tape; a zero rotation guide member carried by the support to move in a plane perpendicular to the axis of rotation;
mounting means for mounting said guide member on said support, said mounting means comprising means for allowing said axis of rotation of said guide member to pivot within certain limits; Featuring a tape loop sensing arm. 8) A scanning means, a tape feeding means, a tape winding means, and a guide means for defining a tape path from the tape feeding means to the tape winding means via the scanning means, the guiding means comprising: , a tape transport device comprising at least one pivotable arm and a tape guide mounted on the arm so as to be pivotable along an arcuate path in a predetermined plane with the arm; The tape guide includes a spindle and a means for attaching the spindle to the arm,
means for limiting the pivot range of the spindle; means for limiting the pivot range of the spindle; It is characterized by comprising a cylindrical guide part surrounding the spindle and having the same width as the spindle, and a bearing for rotatably attaching the guide part to the spindle. tape conveyance device. 9) The tape conveying device according to claim 8, wherein said attachment means defines a pivot axis passing through the center of said guide portion.